Printer

Abstract

A printer has a platen top unit fastened above the platen unit. The platen top unit is separate from the platen unit, and has first star wheels and second star wheels disposed on parallel horizontal frame members extending perpendicularly to the media conveyance direction above the platen surface. The first star wheels and second star wheels prevent the continuous paper conveyed over the platen surface from lifting away from the platen surface.

What is claimed is: 
     
       1. An inkjet printer comprising:
 a platen unit having a platen surface that supports sheet media conveyed in a conveyance direction; 
 a head unit that carries an inkjet head including a first head and a second head that prints on the sheet media, and moves between a print position where the inkjet head is opposite to the platen surface, and retracted position where the inkjet head is retracted from the print position; and 
 a platen top unit including a first frame and a second frame between the platen unit and the head unit; wherein 
 the head unit has an inkjet head lift mechanism configured to move the inkjet head toward and away from the platen surface; 
 the platen top unit is separated from the platen unit and the head unit; and 
 when the head unit is at the print position and the inkjet head lift mechanism moves the inkjet head toward the platen unit,
 a portion of the inkjet head enters a space between the first frame and the second frame in the conveyance direction, and 
 the first frame is positioned between the first head and the second head in the conveyance direction. 
 
 
     
     
       2. The inkjet printer described in  claim 1 , wherein:
 the platen top unit has a gap holding member, and 
 when the head unit is at the print position and the inkjet head lift mechanism moves the inkjet head toward the platen unit, the head unit and the platen unit contact the gap holding member. 
 
     
     
       3. The inkjet printer described in  claim 2 , wherein:
 the gap holding member is a bearing ball. 
 
     
     
       4. The inkjet printer described in  claim 1 , wherein:
 the platen top unit is fastened to a main printer frame. 
 
     
     
       5. The inkjet printer described in  claim 4 , wherein:
 the platen unit moves between an opposing position, and an open position where the platen surface is further from the inkjet head than at the opposing position, and 
 when the platen unit is the opposing position and the head unit contact the gap holding member, specific gap between the platen face and the inkjet head is held. 
 
     
     
       6. A printer comprising:
 a platen unit having a platen surface that supports sheet media conveyed in a conveyance direction; 
 a print head including a first head and a second head configured to be positioned at an opposite position where the print head is opposite to the platen surface; and 
 a platen top unit disposed between the platen surface and the print head, when the print head is positioned at the opposite position, the platen top unit including a first frame; 
 wherein when the print head is at the opposite position, the first frame is positioned between the first head and the second head in the conveyance direction. 
 
     
     
       7. The printer described in  claim 6 , wherein:
 the first frame extends in a transverse direction intersecting with the conveyance direction, and is longer than at least one of the first head and the second head, in the transverse direction. 
 
     
     
       8. The printer described in  claim 6 , wherein:
 the platen top unit includes a second frame, and 
 when the print head at the opposite position, the first head is positioned between the first frame and the second frame in the conveyance direction. 
 
     
     
       9. The printer described in  claim 8 , wherein:
 the platen top unit includes a first longitudinal frame and a second longitudinal frame; 
 the first frame is connected to the first longitudinal frame and the second longitudinal frame; 
 the second frame is connected to the first longitudinal frame and the second longitudinal frame; and 
 when the print head at the opposite position, the first head is positioned between the first longitudinal frame and the second longitudinal frame in a transverse direction that intersects with the conveyance direction. 
 
     
     
       10. The printer described in  claim 6 , wherein:
 the platen top unit includes a first star wheel disposed on the first frame. 
 
     
     
       11. The printer described in  claim 10 , wherein:
 the platen top unit includes a second frame and a second star wheel disposed on the second frame, and 
 the first star wheel and the second star wheel are at different positions in a transverse direction that intersects with the conveyance direction. 
 
     
     
       12. The printer described in  claim 6 , wherein;
 the print head moves to a retracted position where the print head is retracted from the platen top unit, and 
 when the print head is at the retracted position, the print head is not opposite to the platen surface. 
 
     
     
       13. The printer described in  claim 6 , wherein:
 the print head at the opposite position moves between a first head position and a second head position where a gap between the print head and the platen surface is bigger than the gap between the print head at the first head position and the second head position. 
 
     
     
       14. The printer described in  claim 13 , wherein:
 the platen top unit includes a gap holding member, and 
 when the print head is at the first position, the print head and the platen surface contact the gap holding member. 
 
     
     
       15. The printer described in  claim 14 , wherein:
 the gap holding member is a bearing ball. 
 
     
     
       16. The printer described in  claim 15 , wherein:
 the platen top unit includes at least three bearing balls. 
 
     
     
       17. The printer described in  claim 15 , wherein:
 the bearing ball is disposed in the platen top unit. 
 
     
     
       18. The printer described in  claim 17 , wherein:
 the platen top unit includes a bearing ball holder which includes a round through-hole and a wire support member. 
 
     
     
       19. The printer described in  claim 6 , wherein:
 the platen top unit is fastened to a main printer frame.